Point-Of-Gaze Estimation Robust to Head Rotations And/Or Device Rotations

1. A method of estimating point-of-gaze of a user looking at a display, said method comprising: capturing an image of an eye of said user using a camera, said camera interconnected to at least one processor; processing said image using said at least one processor to determine coordinates in said image of a plurality of defined eye features sufficient to determine the optical axis of said eye of said user; determining at least one angle proportional to an angle between (i) a line coincident with an edge of said display and (ii) an intersection of the sagittal plane of the head of said user with a plane of said display; and estimating an intersection of the line-of-sight of said eye of said user with said plane of said display, using the optical axis of said eye, and using said at least one angle to account for rotation of said head of said user or said display.

2. The method of claim 1 , wherein said image is captured to include a plurality of defined head features, and said method further comprises processing said image to determine coordinates in said image of said plurality of defined head features and calculating said at least one angle using said coordinates in said image of said plurality of defined head features.

3. The method of claim 1 , wherein said determining comprises receiving an indicator of said at least one angle from at least one sensor attached to said display or attached to the head of said user.

4. The method of claim 1 , further comprising determining an angle between the optical axis of said eye of said user and the line-of-sight of said eye of said user.

5. The method of claim 4 , wherein said angle between the optical axis and the line-of-sight of said eye of said user is determined at least in part using a predetermined angle reflective of a population average.

6. The method of claim 4 , wherein said angle between the optical axis and the line-of-sight of said eye of said user is calibrated for said user.

7. The method of claim 1 , wherein said estimating comprises: determining the optical axis of said eye of said user using said coordinates in said image of said plurality of defined eye features; calculating a corrective angular offset using said angle between the optical axis and the line-of-sight of said eye of said user and said at least one angle; and applying said corrective angular offset to said optical axis of said eye of said user.

8. The method of claim 1 , wherein said estimating comprises: calculating an approximation of said point-of-gaze using said coordinates in said image of said plurality of defined eye features; calculating a corrective offset for said approximation to account for an angle between the optical axis and the line-of-sight of said eye of said user, using said at least one angle; and estimating said intersection of the line-of-sight of said eye of said user with said plane of said display by applying said corrective offset to said approximation.

9. The method of claim 8 , wherein said corrective offset is calculated using a predetermined offset calibrated for said user for a given orientation of said head of said user.

10. The method of claim 1 , further comprising determining pixel coordinates in a current image coordinate system of said display, corresponding to said estimated intersection of the line-of-sight of said eye of said user with said plane of said display.

11. The method of claim 10 , further comprising receiving an indicator indicative of a change in said current image coordinate system.

12. The method of claim 1 , wherein said plurality of eye features comprises at least one of an iris-sclera boundary, an iris center, a pupil center, a pupil boundary, and a reflection of a light source.

13. A method of estimating point-of-gaze of a user looking at a display, said method comprising: capturing an image of an eye of said user using a camera, said camera interconnected to at least one processor; processing said image using said at least one processor to determine coordinates in said image of a plurality of defined eye features sufficient to determine the optical axis of said eye of said user; determining at least one angle proportional to an angle between (i) a line coincident with an edge of said display and (ii) an intersection of the sagittal plane of the head of said user with a plane of said display; and estimating an intersection of the line-of-sight of said eye of said user with said plane of said display, using said coordinates of said plurality of defined eye features sufficient to determine the optical axis of said eye, and using said at least one angle to account for rotation of said head of said user or said display.

14. A device for estimating point-of-gaze of a user looking at a display, said device comprising: a camera; at least one processor interconnected to said camera; and memory interconnected to said at least one processor, said memory storing software code that, upon execution by said at least one processor, causes said device to: receive an image of an eye of said user from said camera; process said image to determine coordinates in said image of a plurality of defined eye features sufficient to determine the optical axis of said eye of said user; determine at least one angle proportional to an angle between (i) a line coincident with an edge of said display and (ii) an intersection of the sagittal plane of the head of said user with a plane of said display; and estimate an intersection of the line-of-sight of said eye of said user with said plane of said display, using the optical axis of said eye, and using said at least one angle to account for rotation of said head of said user or said display.

15. The device of claim 14 , wherein said image received from said camera includes a plurality of defined head features, and said determining at least one angle further comprises processing said image to determine coordinates in said image of said plurality of defined head features and calculating said at least one angle using said coordinates in said image of said plurality of defined head features.

16. The device of claim 14 , further comprising at least one light source adapted to generate a reflection in said eye of said user, and said plurality of defined eye features includes said reflection.

17. The device of claim 14 , further comprising at least one sensor adapted to provide an indicator of said at least one angle.

18. The device of claim 17 , wherein said at least one sensor comprises a gyroscope or an accelerometer.

19. The device of claim 14 , wherein said display is integral to said device.

20. The device of claim 14 , wherein said device is a mobile phone or a tablet computer.

21. The device of claim 14 , wherein said camera is an infrared camera.

22. The device of claim 14 , wherein said device further comprises a depth camera or a 3D camera.